Only nine of the 62 apartments sold in One Hyde Park – the world’s most expensive residential block – have been registered for council tax.

The ownership of the Knightsbridge apartments, which range in price from £3.6m for a one-bedroom flat to £136m for a penthouse, is now under investigation by Westminster city council, which is determined to pursue the monies owed by the secretive owners of the apartments.

Council records show that only four owners are paying the full council tax of £755.60 a year plus £619.64 to the Greater London Authority, while five are paying the 50% discounted council tax owed on a second home.

Westminster has received no response from the developer of One Hyde Park, Project Grande (Guernsey), managed by billionaire brothers Nick and Christian Candy, to a written request sent two weeks ago asking for the names of the remaining apartment owners. Officials are now researching Land Registry records for the exclusive block, sandwiched between Harvey Nichols and the Serpentine. However, the myriad offshore companies protecting the identities of residents are, according to sources at the council, likely to defeat them.

An analysis of the records by the Observer shows that 25 of the flats’ registered owners are companies in the British Virgin Islands. Other offshore tax havens used to purchase the properties include Guernsey, the Cayman Islands, Liechtenstein and Liberia.